Nutrition chemoprevention of gastrointestinal cancers: a critical review.

Various strategies utilizing specific dietary factors have been investigated for their ability to modulate the development of several cancers of the gastrointestinal tract. The effects of fat, red meat, fiber, fruits and vegetables, and alcohol on colorectal carcinogenesis have been reasonably well defined. Folate, selenium, and omega-3 fatty acids are rapidly emerging as important agents in nutrition chemoprevention, while the role of antioxidant vitamins and calcium is less certain. Although recent intervention studies from China have suggested a protective role of certain vitamins and minerals for esophageal and gastric cancers, further data from prospective randomized intervention studies are needed. Until more firm data are available, the dietary recommendations provided by the American Cancer Society and the National Cancer Institute are appropriate guidelines.